When you have a shop with different countries, BELGIUM and NETHERLANDS for instance, they have different payment providers. Once set different payment providers and a user is NOT logged in but is in the shopping cart. When checking out, it will give a page with the question to choose a payment. There aint one, cause the payment is dedicated to either BELGIUM or NETHERLANDS.
I know I can tick the function that it automatically picks the payment, but that doesn't work if both countries will use paypal!
So this needs to be fixed by the next patch I guess. with an if statement if not logged in, show login/registration page first.